Some elevators use a guide roller arrangement to guide the car on the guide rail, while others use a guide which typically contains a sliding shoe--low friction shoe that slides on the rail. In many of these guides, an elastomeric pad (mount) interconnects a guide shoe retainer--a bracket that is attached to the car. The mount, typically a pad of rubber, absorbs noise and vibration. Its characteristics must be closely matched to the total mass of the car, which includes the frame and the cab. If the elastomer is too stiff, there is inadequate shock and noise absorption, the ride is hard. If it is too soft, the ride is uneven.